The present invention relates to systems for interconnecting remotely located computers.
In a typical local computer network there are a number of client computers that are coupled via a communication link to a number of network server resources. These resources include file servers, print servers, modem servers, and CD-ROM servers for example. Each server is usually a stand alone computer with its own keyboard, mouse and video monitor. Each client computer can utilize the functions provided by the server computers through the communication link.
Most computer networks have one or more system administrators, i.e. human operators, for the server computers. The system administrators monitor the operation of the software running on the server computers, load new software packages, delete outdated files and perform other tasks necessary to maintain the operation of the network. While most administrator tasks (modifying software, deleting files, etc.) can be performed over the network from a client computer, there are some situations where the network administrators must be physically located at the server computers for direct access to and operation of them. For example, it is not possible to reboot a server computer over the network. If the server computers are not close together, the time required for a task as simple as rebooting can be substantial.
Although it is possible to run dedicated communication links to each server computer in order to allow a system administrator to operate the network from a central location, a large number of cables are required for anything other than a very simple network.
The present invention provides a computerized switching system that allows centrally located network administrators to operate multiple server computers over long distances without requiring a complicated wiring scheme. In general, the switching system allows data transmission between a workstation and a remotely located server computer. A signal conditioning unit receives keyboard and mouse signals from a workstation and generates a serial data packet which is transmitted to a central crosspoint switch. The crosspoint switch routes the keyboard/mouse packet to another signal conditioning unit that is coupled to the remotely located server computer. The signal conditioning unit coupled to the server computer decodes the keyboard/mouse packet and applies the signals to a keyboard and mouse connector on the remote computer in the same manner as if the mouse and keyboard were directly coupled to the remote computer.
Video signals produced by the remote computer are transmitted through the crosspoint switch to the workstation. In order to minimize the number of wires extending between the remote computer and the workstation, the horizontal and vertical sync signals as well as a mode signal are encoded with the analog video signals. The present embodiment of the invention allows any of thirty-two workstations to be connected to any of thirty-two remotely located server computers.